1. Field of the Invention
The present invention relates to a system and method for transmitting and receiving signals in a communication system using a relay scheme, referred to herein as a relay communication system.
2. Description of the Related Art
Currently, wireless communications are evolving from 3rd generation wireless communication systems into 4th generation wireless communication systems. 4th generation wireless communication system studies are being conducted to provide higher data rates and to expand wireless transmission regions, service coverages, etc. A multi-hop scheme has been proposed for service coverage expansion. In the multi-hop scheme, a Relay Station (RS) designed with a low cost for communication of Mobile Stations (MSs) located in an edge of the cell coverage, relays signals to the mobile stations located in the edge of the cell coverage. Also, the relay station can relay signals of the mobile stations to a Base Station (BS).
Due to the presence of the relay station, there can be, for example, three types of wireless links including (1) a link between the BS and the RS (a BS-RS link), (2) a link between the RS and the MSs (a RS-MS link), and (3) a link between the BS and the MSs (a BS-MS link). An increase in the number of links may cause an increase in wireless resources used in a system which may have limited wireless resources. In such a case, the system may suffer from more frequent signal interferences, compared to a communication system in which there is only a BS-MS link due to the absence of the RS.
In order to prevent such signal interference problems, it is possible to separate each link by time or frequency and transmit/receive signals over the link. For example, a first time interval or first frequency resource can be used for signal transmission/reception over the MS-RS link, and a second time interval or second frequency resource can be used for signal transmission/reception over the RS-BS link. However, the signal transmission/reception based on the separation of the time or frequency resources has no change because limited wireless resources are used on a division basis.